A device to device (D2D) communication technique which allows direct communication with another UE existing around the UE has emerged to provide a more efficient service using a wireless mobile communication system. A device to device communication technology may perform device to device communication through a discovery operation by a UE for discovering what kind of UEs are present around the UE and through a direct communication operation by the UE with a UE necessary for communication. As such, when the direct communication is performed by the device to device communication, a relatively small amount of wireless resource can be used in comparison with the communication using the conventional wireless network and a base station, and thus the wireless resource efficiency is improved. In addition, since a method for discovering UEs around the UE is supported, information required in accordance with the position of the UE and characteristics thereof can be provided to each UE, and thus new services such as an advertisement service, a Social Networking Service (hereinafter, referred to as SNS), etc. can be created and service efficiency thereby can be improved. Currently, a Long Term Evolution Advanced (hereinafter, LTE-A) system also requires support for the device to device technology and technical discussions therefor are under way.
The device to device communication may communicate using the same frequency band as does a conventional cellular communication which uses a base station. When the device to device communication uses the same frequency band as does the cellular communication, communication can be performed by dividing the communication on a time and frequency axis in order to solve a mutual interference problem. However, when a UE performs the conventional cellular communication, control information such as ACK/NACK, Scheduling Request (SR), Channel Quality Indicator (CQI), etc. can be periodically transmitted to the base station so that the frequency multiplexing may be required between the device to device communication and the cellular communication as well as multiplexing on a time axis. At this time, when the UE performing the device to device communication performs data transmission using an arbitrary transmission power, a problem may occur where in-band emission power thereby can provide a relatively larger noise impact to other UEs than the D2D UE which should receive the transmission. Thus, in a case where the device to device communication technology and the wireless communication technology are used together, in-band emission power due to the D2D signal transmission by the UE using the D2D technology in a system may cause a problem of noise in a cellular transmission, and thus the study for the situation is required.